<!DOCTYPE html>
<html lang="en">

  <head>
    <meta charset="UTF-8">
    <title>04_作用域_面试题</title>
  </head>

  <body>
    <script type="text/javascript">
      var x = 10;

      function fn() {
        console.log(x);
      }

      function show(f) {
        var x = 20;
        f();
      }
      show(fn); //10
    </script>
  </body>

</html>